Cable implies a grouping of multiple conductors, separated with insulation. Only a single conductor is needed for the ground strap so cable is overkill. The real question is braided strap vs. stranded WIRE.
As far as I can see, the only real current that will flow between the engine block and the chassis is that needed for the generation of the sparks. This will be in pulses as each spark plug fires with rest periods between them. Perhaps heat is a concern, but I suspect that resistance is much more of one. Any resistance here would produce a Voltage drop from the 12V battery Voltage and that drop would cause a weaker spark unless the circuitry provides against that. But even that would have it's limits so a good, low resistance connection is needed and is probably the less expensive alternative.
As for braided strap vs. stranded wire, both are used when motion and vibration would eventually cause a solid wire to fail due to metal fatigue from repeated flexing. And if the total cross section area of copper (or other conducting material) is the same, both braided and stranded should provide the same resistance. The choice of one over the other is likely due to more mundane issues, like the cost of terminating the ends. A piece of stranded wire would be round and would need some form of termination, probably crimped terminals on the wire ends or electrical screw style terminal blocks on the engine and frame. A piece of braided strap can have a hole drilled or punched in the end and a simple bolt and washer would then be used to fasten them to the block and the frame. A quick dip in a solder pot before creating that hole will prevent those ends from fraying. A self tapping screw with a drill tip would eliminate two more steps in the process for even greater economy. All of that can cost less than applying a crimped terminal or using terminal blocks. On top of that, crimped terminals or terminal blocks also add two more potential points of failure between the wire and the terminals. So the braided strap without terminals is more reliable.
Since you are not Ford Motor Company or GMC or Toyota and do not have an army of bean counters looking over your shoulder, you can feel free to use the twisted, stranded wire with the appropriate terminals. I would apply some form of corrosion protection after fastening the ground wire in place. Properly installed, it should last just as long.
Doing some preventative maintenance on a 2001 GMC Yukon. So the braided ground strap from the firewall to the engine looks pretty "green" and I'm going to replace it since apparently a bad ground can cause all kinds of hard to solve electrical issues. My question is: why is the strap braided and not a nice insulated piece of stranded cable?
Thanks.
